Featured Research

from universities, journals, and other organizations

Link Between Light Touch And Merkel Cells Solves 100-year Mystery

Date:

June 24, 2009

Source:

Baylor College of Medicine

Summary:

Light touch -- the sense that lets musicians find the right notes on a keyboard, a seamstress revel in the feel of cool silk, the artisan feel a curve in material and the blind read Braille -- truly depends on the activity of Merkel cells usually found in crescent-shaped clusters in the skin.

Share This

Atoh1 expression in Merkel cells in the skin (green) and the nerves that contact them (red).

Credit: Image courtesy of Baylor College of Medicine

Light touch – the sense that lets musicians find the right notes on a keyboard, a seamstress revel in the feel of cool silk, the artisan feel a curve in material and the blind read Braille – truly depends on the activity of Merkel cells usually found in crescent-shaped clusters in the skin, said researchers from Baylor College of Medicine and colleagues in a report that appears in the current issue of the journal Science.

Related Articles

"Human, primates and any animal that relies on hands for dexterity use their Merkel cells to feel texture and shape," said Dr. Ellen Lumpkin, assistant professor of neuroscience, molecular physiology and biophysics and molecular and human genetics at BCM and a senior author of the report. "Merkel cells are not like pain fibers. They exist in special areas of the skin to feel light touch. We have a lot of them on our fingertips and also on our lips."

However, while many scientists thought Merkel cells were key elements of light touch, they could never directly prove the link. The topic has been debated for more than 100 years, since the cell were first described in 1875 by German scientist Friedrich Sigmund Merkel (for whom they are named).

In cooperation with Dr. Huda Zoghbi (another senior author), Lumpkin, first author Dr. Stephen Maricich (now of Case Western Reserve University in Cleveland, Ohio), and colleagues generated mice that lacked a gene called Atoh1 in some areas of the body and, as a result, had no Merkel cells in skin located below the head. Experiments on these mice directly demonstrate the link between Merkel cells and touch in way that can be seen and heard.

That is probably the most significant thing about the paper, said Marichich. While Merkel himself first postulated the link between the cells and light touch, "this is the first direct evidence," said Maricich, who plans to continue working with the cells, determining the progenitor cells from which they arise and determining how they relate to human disease.

A decade ago, Zoghbi, Dr. Hugo Bellen and other BCM researchers identified Atoh1 (also called Math1), and were the first to show it affects hearing and proprioperception – the sensing of where parts of one's body are in space. (See figures 1 and 2)

Zoghbi is professor of pediatrics, molecular and human genetics, neurology and neuroscience at BCM and is also a Howard Hughes Medical Institute investigator.

"To our knowledge, Atoh1 is the first gene shown to be necessary for the specification of Merkel cells," the authors noted in their paper.

To further prove their point, the researchers used special equipment to record tiny electrical impulses that touch elicits from neurons in the skin. In mice that lacked Merkel cells, the skin was missing touch receptors with high spatial resolution (the hallmark of Merkel cells), but was still innervated by other touch-sensitive neurons.

While Merkel cells are probably not involved in proprioperception, Merkel cells and hair cells (the sensory cells of the ear) "allow you to manipulate objects with high spatial resolution and discrimination of sound. That's what I think is beautiful about Atoh1, the Merkel cell and the hair cell," said Lumpkin.

"These cells are the first way our body interacts with the outside world," she said. "Both hair cells and Merkel cells tell us what and when at the finest level we humans relate to our environment."

A decade ago, Lumpkin chose to study Merkel cells at the same time that Zoghbi and Bellen first announced their discovery that Atoh1 (Math1) is necessary for inner ear hair cells. She recognized that the two fields would someday have importance for one another.

Merkel cells are not limited to fingertips or lips, where tactile sensitivity is highest. They are also found in hairier parts of human skin as well as on the bodies of all vertebrates, from fish to primates.

In mice and other nocturnal animals, Merkel cells in the body might be important for maneuvering in the dark. Lumpkin and Maricich plan to use the mice lacking Merkel cells to directly test this possibility.

This is another important component of the Atoh1 network that helps people realize where they are in space, said Zoghbi. While the specific activity of Merkel cells permit light touch and the "what and when" of activity, "Atoh1–dependent neurons are processing that information," she said.

Lumpkin sees the finding as a stepping stone to even more basic answers.

"Bigger than that, we don't know how any mammalian touch receptor works," she said. "What genes allow them to function as light or painful touch receptors? This project gives us the experimental handle with which to start to dissect the genetic basis of touch."

Others who took part in this research include BCM Neuroscience graduate students Scott A. Wellnitz and Aislyn M. Nelson, and Daine R. Lesniak and Gregory J. Gerling of the University of Virginia.

Funding for this work came from the National Institutes of Health, the McNairs Scholars Program, the National Library of Medicine, the Defense Advanced Research Projects Agency and the Howard Hughes Medical Institute.

More From ScienceDaily

More Health & Medicine News

Featured Research

Mar. 3, 2015 — No significant change in home habits of smokers have been observed in the aftermath of a ban on smoking in public spaces, researchers report. Greater inspiration to kick the habit likely comes from ... full story

Mar. 3, 2015 — Heart function has been associated with the development of dementia and Alzheimer's disease through a new study. Participants with decreased heart function, measured by cardiac index, were two to ... full story

Mar. 3, 2015 — Children of recently separated or divorced families are likelier to drink sugar-sweetened beverages than children in families where the parents are married, putting them at higher risk for obesity ... full story

Mar. 3, 2015 — Gastric bypass and similar stomach-shrinking surgeries are a popular option for obese patients looking to lose weight or treat type 2 diabetes. While the surgeries have been linked to a decreased ... full story

Mar. 3, 2015 — Most people consume more salt than they need and therefore have a higher risk of heart disease and stroke, which are the two leading causes of death worldwide. But a new study reveals that dietary ... full story

Mar. 3, 2015 — Twice as many children born to mothers who took antibiotics during pregnancy were diagnosed with asthma by age 3 than children born to mothers who didn’t take prenatal antibiotics, a new study has ... full story

Mar. 3, 2015 — Pediatric otolaryngologists and surgeons are concerned with parents getting the wrong message regarding the safety/desirability of letting babies and young children eat peanuts to prevent them from ... full story

Mar. 3, 2015 — Why do people shake hands? A new study suggests one of the reasons for this ancient custom may be to check out each other's odors. Even if we are not consciously aware of this, handshaking may ... full story

Featured Videos

Mom Triumphs Over Tragedy, Helps Other Families

AP (Mar. 3, 2015) — After her son, Dax, died from a rare form of leukemia, Julie Locke decided to give back to the doctors at St. Jude Children&apos;s Research Hospital who tried to save his life. She raised $1.6M to help other patients and their families. (March 3)
Video provided by AP

Woman Convicted of Poisoning Son

AP (Mar. 3, 2015) — A woman who blogged for years about her son&apos;s constant health woes was convicted Monday of poisoning him to death by force-feeding heavy concentrations of sodium through his stomach tube. (March 3)
Video provided by AP

Related Stories

Jan. 26, 2015 — A population of “progenitor” cells in the skin that are solely responsible for the generation and maintenance of touch-sensing Merkel cells have been identified by scientists. Merkel cells are ... full story

Apr. 15, 2014 — Merkel cells -- which contact many sensory nerve endings in the skin -- are the initial sites for sensing touch, researchers have demonstrated. "Scientists have spent over a century trying to ... full story

Apr. 6, 2014 — Biologists have solved an age-old mystery of touch: how cells just beneath the skin surface enable us to feel fine details and textures. Touch is the last frontier of sensory neuroscience. The cells ... full story

Apr. 6, 2014 — A new study has helped solve a long-standing mystery about the sense of touch. The “gentle touch” sensations that convey the stroke of a finger, the fine texture of something grasped and the ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.